Disclosed in FIG. 13 is a drink product DG obtained by filling a plastic vessel V having a small capacity with a drink. As shown in FIG. 14, to the drink products DG, an overwrap packing is carried out by using a wrapping material PM constituted by a biaxially stretched film having a thermal shrinking property in order to integrally handle a plurality of drink products DG. In an overwrap packed body in which a plurality of drink products DG are wrapped with the wrapping material, as shown in FIG. 14, a small hole p is formed on the wrapping material PM in each gap portion between the adjacent drink products DG. The wrapping material PM is broken when a small hole P portion is pushed with fingers, and the packed drink product DG can be thus taken out.
However, when the overwrap packing is carried out over the drink products DG by using the wrapping material PM provided with the small hole p in advance, there is a possibility that the small hole p formed on the wrapping material PM might depart the gap portion between the adjacent drink products DG. That is, it is difficult to surely form the small hole p in the gap portion between the adjacent drink products DG in the overwrap packed body. Furthermore, a sufficient breaking property cannot be maintained by only the formation of the small hole p on the wrapping material PM as a starting point for breaking the wrapping material PM.
In addition, when the perforated line formed on a thin film forming a wrapping material, the following method is employed, in related art of the present invention. That is, as shown in FIG. 15, there are used a cutter roller CR having a large number of perforated line forming blades c provided at a predetermined interval over a whole periphery and a guide roller GR provided with a peripheral groove g for receiving the perforated line forming blade c of the cutter roller CR.
The film F is fed on the guide roller GR, and the cutter roller CR is rotated in a state in which the perforated line forming blade c is inserted into the peripheral groove g formed on the guide roller GR. At the peripheral groove g portion formed on the guide roller GR, a perforated line is formed on the film F, by sequentially sticking the perforated line forming blade c to the film F.
When a plurality of perforated lines are formed on the wrapping material in parallel at a small interval, the plurality of perforated lines are formed at the same time by forming a plurality lines of perforated line forming blades c on the single cutter roller CR, in the related art. However, if the interval between the perforated lines is small, it is difficult to individually form, on the guide roller GR, a plurality of peripheral grooves g respectively formed for receiving the plurality lines of perforated line forming blades c. Thus, as shown in FIG. 16 as related art of the present invention, a single peripheral groove g1 for receiving the whole lines of perforated line forming blades c is formed on the guide roller GR.
When a plurality of perforated lines is to be formed at the same time in the wide peripheral groove g1 portion for receiving the whole lines of perforated line forming blades c, the amount of elongation and that of shift in the film F in the peripheral groove g1 portion are more increased as compared with the case in which a plurality of peripheral grooves is individually formed on the guide roller for each of the perforated line forming blades. Therefore, as shown in FIG. 16, the amount of sticking of the perforated line forming blade c to the film F is reduced. Particularly, the amount of sticking of the perforated line forming blade c constituting a central line is reduced. As a result, a proper perforated line cannot be reliably formed.
Moreover, if close perforated lines are formed at the same time even in the case the peripheral grooves g for individually receiving the plurality lines of perforated line forming blades c is formed on the single guide roller GR, both side portions of each of the perforated line forming blades c in the film F are stretched toward the respective perforated line forming blade c sides, when the perforated line forming blade c sticks to the film F. Therefore, that the film F is broken at a cut portion constituting the perforated line formed on the film F by a tensile force and the film F is thus apt to be damaged.